Disclosed in Japanese Patent Laid-open Publication 1999-094203 is a steam generator adapted for use in a cooking appliance of foodstuffs, which comprises an upright boiler in the form of a vertical cylindrical body provided with an electromagnetic induction heater and connected at its lower end to a header for connection with a water supply system and a drain system, a vertical bypass duct connected at its intermediate portion with a steam discharge pipe laterally extended from the upper end of the cylindrical body of the boiler, and an upstanding pipe connected at its lower end to the header for detecting a level of water in the boiler. In the steam generator, steam introduced into the bypass duct through the discharge pipe spouts upward, and drops of hot water separated from the steam fall in the header and are circulated into the interior of the boiler.
Because in the conventional steam generator, the bypass duct causes drops of hot water contained in the steam to fall in the header connected in common to the water supply system and the drain system, it is difficult to assemble the bypass duct and the upright boiler in a limited space for manufacturing of the appliance in a small size. Because in the conventional steam generator, the interior of the upstanding pipe for detection of the level of water in the boiler is heated, it is likely that a detection sensor disposed in the upstanding pipe would be damaged by heating.